Decomposition of multilevel objects in an object-oriented database

Logical foundations of multilevel databases

“…This particular MultiView model for an object-oriented database has already been presented in several papers [BCGY93a,BCGY93b,BCGY94a,CG96a] and some of its results have been reused in other security models [SMKL95]. Compared to the previous versions of this model, the new version presented in this paper shows two main improvements:…”

“…We propose to implement this axiom as follows: For all these level l', Val v (o,a,v,l') is evaluated using a pointer to the view at level l. This pointer value is a syntactical expression which enables the system to automatically retrieve the value v from the database of level l (see [BCGY94a] for more details).…”

“…This pointer is actually a syntactical expression of the form "(FireFox,U).Speed". More can be found about these pointers in [BCGY94a]. Notice that thanks to these pointers, an update to an attribute value at a low level would be automatically propagated to the higher levels.…”

Mandatory security and object-oriented systems: A multilevel entity model and its mapping onto a single-level object model

“…As for object-oriented systems, other authors [3,4,9,10,13] have proposed the use of single-level objects and have illustrated, or simply sketched, how multilevel entities can be represented.…”

“…Although protection in object-oriented systems presents substantial differences due to the different semantic constraints and expressiveness of the two data models, some concepts proper of the mandatory policy which have been extensively investigated for the relational model also apply to the object-oriented model. With respect to the work in relational databases, we note that the borrow option has some similarity with the derived values first introduced in the LDV multilevel relational database model [7] and further developed in [4] and [6]. In these approaches, when for a given attribute no value is specified at a certain level l, the value is derived from the highest level below l for which a value is specified.…”